The Western Australian government has increased its rules for New South Wales residents following a cluster of COVID-19 cases on Sydney's northern beaches, with arrivals now required to self-quarantine for 14 days.

United is slated to kick off its 2020-21 campaign against Perth Glory at Dorrien Gardens on Tuesday, December 29. But who will be available remains to be seen.

The bulk of Vicki Linton's squad are NSW residents which casts a major cloud over their availability for the opening round clash.

It's understood the W-League is monitoring the situation and the club is working with the governing body for further guidance.

State governments were prompted to tighten their borders after the cluster tripled to 17 cases overnight, with Canberrans advised not to travel to the northern beaches and anyone who recently returned must self-isolate.

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The cluster has since grown to 28 with another 10 cases confirmed on Friday morning.

It's possible United players may not be allowed to return home to Sydney for Christmas, as it would potentially make them ineligible to fly into Perth for their opener on Tuesday week without quarantine.

A-League matches in Perth will not begin until January 16 but their women's side will host two matches before then, with the Newcastle Jets also slated to play at Dorrien Gardens on January 10.

WA health authorities reclassified NSW as a 'low risk' state from 12.01am Friday, bringing in requirements for arrivals to self quarantine for two weeks to immediate effect.

It forced the Canberra Cavalry to withdraw from their opening ABL series against the Perth Heat on Friday, with the majority of their squad unable to play under WA's travel restrictions.

The 2020 Sydney to Hobart is also in doubt, with organisers holding crisis talks on Friday afternoon.

WA Premier Mark McGowan could reintroduce a hard border with NSW, should health authorities recommend the state do so.

"There is no doubt NSW is on the verge of a serious outbreak and we must do whatever is required to keep us safe," McGowan told reporters on Friday.

United, meanwhile, will continue to intensify their preparations leading into round one and are scheduled to meet the Western Sydney Wanderers in Blacktown for a friendly on Saturday.

Selectors have started narrowing down their options for United's starting XI, with the pre-season match an opportunity for the coaching staff to test combinations and assess where the team is at.

Winger Nicki Flannery said the team is training and preparing for round one as normal, despite a cloud looming over their season's start.

"We haven't been notified as such, we're preparing as if round one is still going ahead and that's where our mindset is at. It throws a spanner in the works," Flannery said.

Following the Glory clash, United will host two matches at Viking Park against Sydney FC (January 3) and reigning champions Melbourne City (January 10).